The present invention relates to a generator for a vehicle, and particularly relates to an improvement in a partition plate provided on a brush holder and in brackets.
FIG. 1 is a sectional view of a conventional vehicle generator. In the drawing, the generator comprises a shaft 1 to which a pulley 2 is fixed with a nut, a rotor 3 fixed to the shaft 1, fans 3a fixed to the rotor 3 at its both ends respectively, front and rear brackets 4 and 5 for rotatably supporting-.the rotor 3 through bearings 6 and 7 respectively, a stator 8 disposed at an outer circumference of the rotor 3 and fixed between the front bracket 4 and the rear bracket 5, a rectifier 9 attached to a bottom portion of the rear bracket 5, a brush holder 10 attached to another bottom portion of the rear bracket 5, and a partition plate 11 fastened together with the brush holder 10 and composed of a radial portion 11a and an axial portion 11b as shown in FIG. 3. The rear bracket 5 has a casing 5a provided on the brush holder side and a ventilating hole 5b provided through the casing 5a. FIG. 2 is a broken enlarged view of the brush holder 10 and the casing 5a, in which the brush holder 10 has terminals 10a and 10b and pigtails 10c and 10d.
The operation of the vehicle generator is as follows. If the generator is driven by a not-shown vehicle engine, the fans 3a are rotated, so that the air moved by the fans 3a is subjected to centrifugal force to thereby move toward an outer circumference of the fans 3a, whereby air streams shown by arrows a and b are generated. The radial portion 11a of the partition plate 11 is used as a side plate for improving the efficiency of the fans 3a.
When a key switch is turned on, a battery voltage is applied to the terminal 10a and the pigtail 10c of the brush holder 10, so that a current is caused to flow into a field coil of the rotor 3 to thereby generate a magnetic field. Next, the generator is driven to rotate so that an AC induced electromotive force is generated in the stator 8. The thus generated AC induced electromotive force is rectified into a direct current by the rectifier 9, so that DC power is fed to an electric load of the vehicle or to a battery to charge the same. The axial portion 11b of the partition plate 11 is provided between the bracket 5 and the terminals 10a and 10b or pigtails 10c and 10d of the brush holder 10.
Being arranged as described above, the conventional vehicle generator has problems in the following points. That is, even if the generator is arranged as shown in FIG. 4, the generator often becomes into the state as shown in FIG. 5 when the generator is mounted onto the engine. In this case, the brush holder side casing 5a of the rear bracket 5 is turned downward, so that when water comes in through the ventilating hole 5b of the rear bracket 5 in running of the vehicle in rain, in washing of the vehicle, or the like, the water W gathers, due to surface tension, between the brush holder 10 and the axial portion 11b of the partition plate 11 and between the axial portion 11b and the rear bracket 5 as shown in FIG. 6. Accordingly, electrolytic corrosion occurs between the terminal 10a or the pigtail 10c of the brush holder 10 having a certain potential and the rear bracket 5 which is an earth side, so that the terminal 10a or the pigtail 10c is disconnected, resulting in defective power generation.